How does the affect earth's atmosphere?

Answer 1

That's a very general question. In the broadest sense, Earth's atmosphere allows life to exist on the Earth. It's a mixture of approximately 78% Nitrogen, 21% Oxygen, and the remaining 1% of other gases (primarily argon). Oxygen, of course, is essential for animal life, and the carbon dioxide in the atmosphere allows for plant life. The atmosphere consists of 5 layers. The outermost layer, the Exosphere, is essentially space with some floating air molecules. The next innermost layer is the Thermosphere, and is, surprisingly, quite prone to extreme temperatures (temperatures are often much higher during daylight and colder during nighttime than Earth's surface at the same time). The next innermost layer is the Mesosphere, where the coldest temperatures on Earth may be found. Going inwards again, the next layer is the Stratosphere, which is particularly important because it contains the ozone layer, a layer of molecules (O3) which absorb harmful UV rays. Without the ozone layer, life could not exist in its present form. And finally we arrive at the Troposphere, which lies directly upon the Earth's surface. The air we breath is trapped in this layer, and much of our weather exists in this layer.